Joint structure for metal tubing



July 14, 1953 E. c. BooTH A 2,545,276

JOINT STRUCTURE FOR METAL TUBING l Filed sept. 1. 1949 INVENTOR. Enel. C. @aar-H,

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I ABy 2i E ATTORNEYS.

Patented July 14, 1953 2,645,276 JoINT STRUCTURE Fon METAL TUBING Earl Booth, Columbus, Ind., assignor to Arvin f Industries, Inc., a corporation of Indiana Application yseptemlmr 1, 1949, serialNo. 113,550 I 'I'his invention relates to furniture and other articles constructed of metal tubing and more particularly to a structure embodying cylindrical legs and one or more tubular stretchers extending between and secured to such legs. It is an object of the invention to provide for such a structure a stretcher which will serve both to interconnect the legs between which it extends and also to provide feet for such legs.

In carrying out the invention, a length of metal tubing of which a stretcher `is to be formed is cut obliquely Vat its ends, the planes of the two cuts converging upwardly with respect to the position which the stretcher is'to occupy in the iinished article. The metal along the upper portion of each cut end is next displaced outwardly of the tube to form a short semi-cylindrical flange having an 'internal diameter approximating the external diameter of the leg with which the flnished stretcher is to be connected. A cylindrical punch is then inserted through such cylindrical flange transversely of the tube-axis and, in cooperation with an appropriate die, forms the end of the tube into an upwardly opening, leg-receiving socket the lower end of which is offset downwardly from the lowermost point of the f tube-wall.

The accompanying drawing illustrates the invention.

Fig. 1 is a side elevation of a collapsible chair which shows, by way of examplathe manner in which the invention is embodied in an article of furniture; Figs. 2 and 3 are sectional views il'- lustrating the two sets of dies employed in the formation of a stretcher-end; Fig. 4 is a fragmental front elevation of a leg and stretcher in assembled relation; Fig. 5 is a section on the line 5-5 of Fig. 4; and Figs. 6 and 7 are fragmental elevations showing the stretcher in two intermediate stages of its function.

The chair shown in Fig. l, which is illustrated merely as an example of articles of furniture and other structures in which my invention may be incorporated, embodies a pair of side frames each comprising a front leg I0, a rear leg I l, and a stretcher I2 which rigidly interconnects the two legs. Both legs and the stretcher are formed of metal tubing. The chair as a whole forms the subject matter of my prior United States Letters Patent No. 2,608,240, granted August 26, 1952, and constitutes no part of the present invention.

In the following description of the manner in which each stretcher is formed, it is assumed for the sake of convenience that during its forma- 3 Claims. (Cl. 155-196) `2 tion the stretcher occupies the same position about its axis as it does in the finished chair.

The length of tubing from which each stretcher is to be formed is cut off obliquely so that its two end faces I3 (Fig. 6) converge upwardly. The angle which 'the plane of each end face I3 makes with the axis of the tubing is desirably somewhat less than 45. `As a first step in the formation of the stretcher, the tubing is brought into association with a divided die I5 having a cylindrical recess whichwhen the die is. closed, provides exterior support for the tubing over all portions of the outer surface thereof lying to the left and below the chain lineV I4` of Fig. 6. With the tubing so supported in the die I5 a punch'v I6 is then inserted axially into it; Such punch has a pilot portion II and a laterally projecting shoulder I8 which, in plan, is semiecircular in shape and has a diameter approximately equal to the diameter of `the legs I0 and I I. As the punch I6 is forced h ome, that portion of the tubing I2 which lies above and to the right of the broken line I4 and which is unsupported by the die I6 is distorted to conform to the nose of the shoulder I8. This bent metal forms a short flange I9 (Fig. '7) which is generally semi-cylindrical in plan and which has an interior diameter approximately equal to the outer diameter of the leg which it is to receive.

After the flange I9 has been formed on one end of the stretcher, the die I5 is opened, the stretcher is reversed and a similar flange I9 is formed on the other end.

For the next step in the formation of the stretcher, its ends are successively subjected to the action of the die combination illustrated in Fig. 3. The die 2| shown in Fig. 3 has a sha1- low, upwardly opening cylindrical recess 22 and, extending laterally from a point above each recess, a semi-cylindrical groove which provides support for the stretcher I2 over the lower half of its circumference. A punch 24 alined with the recess-22 has an external diameter approximately equal Ato the diameter of each of the legs I0 and II. With the punch 24 elevated, the stretcher. I2 is placed in the die 2I in such a position that the descending punch will engage the inner face of the flange I9. If desired, the punch 24 when elevated may be so disposed that its lower end is only slightly above the axis of the stretcher, in which event Vthe flange I9 may be seated against the side of the punch in order to locate the stretcher I 2 in proper position both axially of itself and angularly -about its axis. When the punch 24 is lowered, the end of the tubtheyare embodied are inuse.

. ing is formed to provide an upwardly opening socket adapted to receive a leg having a diameter equal to that of the punch 24. As the bottom of such socket is oiset downwardly below the lowermost point of the body of the stretcher, the socket forms a foot when the stretcher is embodied in an article of furniture.

After one end of the stretcher is formed t0 lprovide a socket, the ,stretcher is reversed in the Adie 2|, .and a socket is formed on the other end. In assembling the finished stretcher with the legs I0 and H, the lower ends of the legs are placed in the socket and secured therein preferably Vby brazing.

If desired, each of the sockets may be provided in its bottom with an opening adapted to permit the escape of any paint which may enter the interior of the tubular members while they are being painted as well as to permit the escape v of any water which may enter the tubular members when the' articles of Afurniture in which Whenrsuch openings are desired they may be formed by a punch v26 'as :an incident to formation of each socket.

If such .openings are employed, I have found it desirable to formthem so that their peripheries will be deflected inwardly, as shown in Fig. 3, to

constitute a flange which will forni the lower In the finished article of furniture, the sockets on" the ends of each stretcher serve not onlyY to interconnect the stretcher and legs but also Vprovide the feet necessary to'` provide adequate bearing area for legs formed of tubing.` Cost of manufacture is reduced, as the foot is formed in the same Yoperation vby which the stretcher-end ,is brought into conformity with the leg, and it is therefore unnecessaryto provide and assemble Ya foot as a separate article of manufacture.

. I claim as my invention:

. 1 In afabricated structure, a pair of spaced portion of the socket intoa trap forV any melted Y spelter entering the socket during the brazing.- sof thelegs in place.

the associated leg. l0

, stretcher comprising a metal tube'deformed at one end to provide an integral socket projecting laterally of the tube in one direction to form a foot and opening laterally of the tube in the opposite direction, the end of one of said legs being received and secured in said socket, each socket having a bottom overlapping the lower end of the associated leg.

3. The invention set `forth in claim 2 with the .addition that theleg vreceived in said socket is tubul'an the bottom of said socket being -provided' with an opening connecting .with .the Vinterior .of the tubular leg.

EARL discern.

References Cited in the le of this `patent UNITED STATES kPATENTS c Numberl Name y Date 384,887 Brott June 19, -1888 398,027 Casler Feb. 19, 1889 1,286,629` Herzog Dec. 3, 1918 1,976,031 Lowenberg` Oct. 9, 1934: 2,105,241 Gazey Jan 1l, 1938 2,125,985 Bond 'Al/ig. 9, 1938 2,331,552 Heidel Oct. 12, 1943 2,522,394 Myers Sept. l2, 1950 FOREIGN PATENTS Number Country Y' DateV 598,361 France Sept. 2,6, 1925 

